Looking for a used par meter

[saltyfilmfolks]

a nice thread.
https://www.reef2reef.com/threads/l...ats-the-difference.237738/page-2#post-2780385
dont get hung up on numbers.

 

[Greenstreet.1]

So what constant would I use ?

 

[saltyfilmfolks]

So what constant would I use ?

45-52 k

45 to 50 k at the med of 52 as sunlight an 67 as best and average the middle. not much difference.
to really to get really realy close you do need a par meter.
as I dont know the age of bulb or quality of led.(its a phone too) etc there is a certain margin of error. And if its 50 to 100 par. well, thats not bad.

but knowing you have high quality gear and very good intensity, your well ahead of the game. and the only difficulty is few low light corals until you know what you have on the bottom

 

[saltyfilmfolks]

And from the led LUX conversion article.

" Use these results with some caution - in most cases it would be safe to assume the results will be low."
caution

 

[chefjpaul]

I'll give this a shot this weekend.

 

[Greenstreet.1]

Thank you guys. Looks like I need to get a par meter I have been fighting it to long. But this lux meter did help me solve a problem as to why I lost two new frags to much lux or par to fast.

 

[saltyfilmfolks]

Thank you guys. Looks like I need to get a par meter I have been fighting it to long. But this lux meter did help me solve a problem as to why I lost two new frags to much lux or par to fast.

dang, sorry. been there.
even knowing the numbers acclimation and knowing the species is important. Plus the trial and error.

 

[Scott.h]

My meter just came. With my leds running at 80% with a 50-50 split blue-and-white I'm 1500 lux with the meter laying on the sand 17 inches down. 8500 right underneath my glass lid but just underneath the water surface. 27000 right under the light without the glass. And I didn't notice not that it's a problem but this specific meter by Milwaukee only goes to 50,000

 

[Scott.h]

Btw that's a current-USA orbit marine 36" programmable light bar model 5102

 

[Scott.h]

Can that be right? If it's 1500 lux at the sand and I'm averaging out the blue and white, dividing 1500 by 57 that gives me a par of 56? I have a few things at the sand that are doing great. Am I mis calculating?

 

[saltyfilmfolks]

My meter just came. With my leds running at 80% with a 50-50 split blue-and-white I'm 1500 lux with the meter laying on the sand 17 inches down. 8500 right underneath my glass lid but just underneath the water surface. 27000 right under the light without the glass. And I didn't notice not that it's a problem but this specific meter by Milwaukee only goes to 50,000

For give the cut and paste. Try a constant of 67 from here.
https://www.reef2reef.com/threads/lux-meter-par-meter-whats-the-difference.237738/page-4


Lux is a measurement of light intensity. from 0(dark) to 100,000(average daylight)
Foot-candles are( if you are a photographer,) another standard of light intensity. Metric/english standard so to speak.

PAR is the amount of usable light for photosynthetic organisms. photosynthetically active radiation.
Intensity and color spectrum both play a part in building PAR

Buy measuring LUX (intensity) and using one of the lighting type specific conversion factors listed. you can closely gauge the amount of PAR in that lamp.
http://www.advancedaquarist.com/2008/2/review

In my 30G cube. At the top of the water. I have an average of 40,000 lux of intensity.
I have a Radium Blue Metal halide over it.
40,000 lux/51=784
Lux ÷ Constant = µmol·m2·sec par

now do the same math at at "Only" 25000 lux
25000 lux / 51 = 490
.

interestingly the coefficient of the sun is 51
That is not the saying the color of the light sources are similar spectrally, just that the amount of PAR is similar.

The coefficient of a cool white tube is 74. so at 40,000 lux is 540par. sounds good Right???
BUT the spectrum of that lamp contains High levels of Red Orange and yellow that will grow green Plants(ugly algae for us) way to much,
For an orchid grower like my wife, that is a good thing, and why PAR meters are used in agriculture too. And why we pay special attention not only the PAR(and its component Intensity) but the spectrum contained in the light source.

FWIW I don't concentrate on the intensity of the source, I focus on the spectrum, but, the reason I write these crazy things, is had there been a more clear explanation of this process and relationship, I would have had much greater success in reefkeeping in the past. BY simply adding one tube of good spectrum to increase its intensity. with dimmers now, that's easy. So dont short your self and also dont burn stuff, and acclimate.

Light is just one parameter to be tested. And if its testing well with your API(lux) test than go Hanna(par)

 

[saltyfilmfolks]

Can that be right? If it's 1500 lux at the sand and I'm averaging out the blue and white, dividing 1500 by 57 that gives me a par of 56? I have a few things at the sand that are doing great. Am I mis calculating?

and yes, 26,000k lux sounds right. Not sure how deep your tank is. That fixture does not seem to have very good "deep" penetration.

and also do some google research on par maps and make comparisons.
check out melevs reefs he has a very good one.

 

[jjbunn]

That's about it....the 67 is due to the color differences of a particular LED fixture (or halide/T5 bulb) from sunlight.

If you're just talking about sunlight "generically" the math is simple...these are all equal:

• "direct sunlight" at sea level
• 100,000 lux
• 2000 PAR
• 1000 watts/square meter

And honestly, I don't even try to be more accurate than these simple conversions. It works. 100,000 lux / 2000 PAR = 50 That's nice, easy math.

That said, if you have a lux meter and a PAR meter at the same time, that's how you make a conversion factor.

Once you know one equivalent measurement for your light from both meters, you have a valid conversion factor for all future lux measurements. Realizing that kinda de-mystified PAR for me.

But don't let this be anti-PAR-meter....use whatever meter you can get your hands on. A PAR meter will techincally be more accurate by some percentage (see: conversion factors) but a lux meter is not so inaccurate to be useless.

It works just find for this purpose: Shoot for around 40,000 lux - anywhere in that vicinity - and your corals should be happy.

The "complete range" for for corals - should you want a "shallow water" or "deep water" environment for example, is from around 20,000 lux to 80,000 lux. Inside that range seems safe for most corals. Some corals do fine above and below that range, but be watchful if you're using that much/little light for the first time...it can definitely stress corals.

The Samsung S4 Android phone has an RGB(W) light sensor (a Capella CM3323) which I've been experimenting with. It gives values for lux intensity in Red, Green, Blue and White, all in a range 0 to 65536 lux. I wrote an app to show the live values, and have been checking them under a Mars Aqua 165W LED array. It's also possible to get a color readout for each LED in the array individually, by positioning the sensor just underneath it.

My understanding is that Lux measurements are not easily converted to PAR, as lux is adjusted for the sensitivity of vision to different colors, whereas PAR is a full, flat spectrum measurement. Have I misunderstood?

I'm wondering if it's possible to derive PAR numbers from the RGB(W) Capella lux sensor values, by tabulating some calibration values. To that end, perhaps someone has PAR measurements for the Mars Aqua (or the individual LEDs in it) that they'd be willing to share?

 

[saltyfilmfolks]

The Samsung S4 Android phone has an RGB(W) light sensor (a Capella CM3323) which I've been experimenting with. It gives values for lux intensity in Red, Green, Blue and White, all in a range 0 to 65536 lux. I wrote an app to show the live values, and have been checking them under a Mars Aqua 165W LED array. It's also possible to get a color readout for each LED in the array individually, by positioning the sensor just underneath it.

My understanding is that Lux measurements are not easily converted to PAR, as lux is adjusted for the sensitivity of vision to different colors, whereas PAR is a full, flat spectrum measurement. Have I misunderstood?

I'm wondering if it's possible to derive PAR numbers from the RGB(W) Capella lux sensor values, by tabulating some calibration values. To that end, perhaps someone has PAR measurements for the Mars Aqua (or the individual LEDs in it) that they'd be willing to share?

https://www.reef2reef.com/threads/lux-meter-par-meter-whats-the-difference.237738/page-4

and then youll make me a PAR APP???
read up on Dana Riddle in advanced aquarist.

 

[jjbunn]

https://www.reef2reef.com/threads/lux-meter-par-meter-whats-the-difference.237738/page-4

and then youll make me a PAR APP???
read up on Dana Riddle in advanced aquarist.

The more I read, the more confused I get, but I think that what is needed is a few measurements of the lux at various positions under e.g. the Mars Aqua fitting, and the measurements of PAR at the same locations under the same fitting. With that data, a fit might be possible to a function that maps between the two. I may simply have to get a PAR meter in order to make the app.

You are welcome to have a copy of the app, of course

 

[saltyfilmfolks]

or use lux to set levels and use the constant to determine par. Dana has already done that for us. that mars is between a 54 and a 70 constant. more likely a 57. or less.
mt MH is also a 57, but has a much sweeter natural spectrum not the cheap piece of import that it. and a reefbrite will have a higher constant. AI prime too.67 to 73.
get it?

 

[saltyfilmfolks]

so you can assume a "constant" number to do the math with based on quality of the lamp.

 

[jjbunn]

so you can assume a "constant" number to do the math with based on quality of the lamp.

Looks like someone has already made the measurements I need for the Mars Aqua:

https://docs.google.com/spreadsheets/d/16_2uFw9unrbYN8OWpmcSb2XlT9vMtnhR_e3lnUhgRLQ/edit#gid=0

What I need to do is make measurements with the Capella sensor, under the Mars Aqua, at the same intensity settings, which will give me values RGBW, and then fit a function par = f(RGBW) that best matches the Lux readings in the table above. The (vain?) hope is that then the function will also work for other types of light ... i.e. the par values from f(RGBW) will be correct for metal halides etc..

 

[mcarroll]

https://www.reef2reef.com/threads/lux-meter-par-meter-whats-the-difference.237738/page-4

and then youll make me a PAR APP???
read up on Dana Riddle in advanced aquarist.

If you look around the plant forums a bit, people have converted our trusty LX-1010B to be a PAR meter with some simple mods to the sensor.

Yes, for curiosity, I'd like one too - but I still can't get around the fact that I'm getting the job done with a $15 LX-1010B and just measuring at the water surface.

 

[mcarroll]

The more I read, the more confused I get, but I think that what is needed is a few measurements of the lux at various positions under e.g. the Mars Aqua fitting, and the measurements of PAR at the same locations under the same fitting. With that data, a fit might be possible to a function that maps between the two. I may simply have to get a PAR meter in order to make the app.

You are welcome to have a copy of the app, of course

Definitely read everything by Dana Riddle that comes up under a google search for "riddle lux par".

Technically, every unique light source has its own unique lux-to-par conversion factor. And yes, taking parallel reading with the two meters is how you get a conversion factor.

The reality is that most reef lights are very similar to each other spectrally, so the conversion factors we'd use would all be fairly similar too.

For what it's worth, I only measure in lux....for our purposes it is accurate enough. The only time I convert to PAR is when I'm dealing with someone who's only measured, or read about, PAR so far.